Spark plug



March 31. 1925.

L. G. HOWARD SPARK PLUG Fed Nov. 25,. 1922 .Patented Mar. 31, 1925.

UNITED STATES PATENT OFFICE.-

LORENZO G. HOWARD, OF PROVIDENCE, RHODE-ISLAND.

SPARK PLUG.

Application mea November 23, 1922. serial No. 602,794.

To all 'whom 'it may concern Be it known that I, LORENZO G. HOWARD,

ing of the device at the spark terminalsy l without removing the plug from the cylinder, andl with these objects in view, the invention consists in a construction, combination and relation of parts of which a preferred embodiment, is illustrated in the accompanying drawings, wherein:

Figure 1 is a longitudinal. sectional view.

Figure 2 is an inner end view of the improved spark plug. I

Figure 3 is a detail sectional view of a slight modification wherein the intensifier feature is omitted.

The structure embodies essentially a shell 10 threaded as usual and as indicated at 11 for engagement with the opening in the cylinder head and fitted at its outer end with a shell nut 12 to form an annular seat 13 for the reception of an annular enlargement at' an intermediate portion of the length of the insulating core which extends through the shell and carries the main electrode 14, said core being of sectional construction and consisting in its illustrated form of allower main or body section 15, an upperor outer section 16 and an intermediate section 17. The separation between the main and intermediate sections of the core is indicated at 18. Cushioning rings 20 and 21 are interposed,I between the surface of the enlargement and the wall of the shell. The inner end of the shell nut serves upon the tightening of the nut to bind the core in its place in the 'shell and hold the sections of the core in their proper relative positions. Preferably an interlocking relation is established between said core sections by providing one of them with a tongue l' 22 to engage a socket 23 in the other. This feature serves to break the joint between the sections and insure a relative centering thereof. Likewise the upper and outer section 16 of the core and intermediate section are interlocked, by providing the latter with a socket 24 for the reception of/ a tongue 25 on the core section 17, and the main electrode which consists of a rod eX- tension axially through said core sections Aand through the interlocking elements of those sections, with a collar 26 in contact with the lower end of the section 15 and a binding nut 27 engaged with a threaded portion of the rod and bearing upon the outer end o'f the upper or outer section 16 'so as to lock the parts against relative longitudinal displacement.

The main electrode, in the construction shown in Figure 1, is divided to form a' spark gap 28.serving asa spark intensifier and also as a means of indicating the proper functioning of the ignition circuit for the connection of which said electrode vis pro- -vided with the usual -binding nut 29, and

this gap is arranged in a gap chamber 30 bounded by a wall 31 of glass or other light penetrable material fitted at its lower end on the terminal core'section. 16 and at its upper endin a cap block 32 which is secured to said terminal core section by bolts 33 which preferably pass through said terminal core section and engage a retaining ring 34, located in the upper end of the hollow shell nut. The outer terminal portion 14a of the electrode is adjustably mounted in the cap block 32 to provide for varying the extent of the spark gap and is movable and secured at its desired adjustments by nuts 35-'35.

' In the modified construction indicated in I Figure 3 the spark gap feature just described is omitted and the terminal section 16a of the insulating core constitutes the outer end of the spark plug and is held in place as previously described by the main electrode 14b which is fitted with'a binding nut 27a.

For cooperation with the. main or positive electrode there is provided the ounding or negative electrode 36 bodlly em-- attached' to a sufficiently to forma small spark gap visible through the upper end of the shell nut and serving as a telltale or indicator of the p roper functioning of the spark terminals at the inner end of the plug, The grounding disk which is seated upon a shoulder of the intermediate core section 17 is held in place by an insulating gasket 38 upon which bears a transparent -annular panel 39 of mica, er its equivalent, in turn secured by the retaining collar 34 upon which bears the inner end of the terminal core section 1,6.

Instead of having the ignition spark gap formed directly between the terminals of the main and grounding electrodes it is preferred to employ a bridging terminal 40 dis- -posed transversely of the spark plug axis in spaced relation with the extremities .of the bore of said terminals and supported. at one end by a tie rod 41 whichis imbedded in and extends. longitudinally ofthe main pr body section of the core and is offset or provided with a hook 42 and at its outer end engaged with the outer end` of themain or body sectionvof the core and held in place against movement permitting rotation of the rod by the contacttherewith of the adjacent end o f the intermediate core section, to the end that the bridging terminal may be permanently held in proper relation with the extremities of the electrodes.

The construction and arrangement of the bridging terminal facilitates the cleansing thereof or the removal therefrom of any accumulations of carbon and at the same time minimizes the tendency of carbon to deposit thereon due to a vibratory characteristic thereof vincidental to the support of said terminal at one end only, and in addition said terminal by reason of its transverse arrangement below the inner end of the block, and the anchorin of the tie rod in the core at an intermediate portion of the length of the latter, serve to prevent any f shattered or fractured portions of the core which may become detached by heat from dropping into the cylinder. The core is thus reinforced by both the main and grounding electrodes and the means employed to support the bridging terminal with the collar 26 of the main electrode and the transversely disposed terminal LICO-serving as a means for preventing the dropping of portions of the core from the inner end of the plug, At the same time the carrying of the grounding electrode outwardly through the core to a lane near vthe open end of the shell nut aflldrds an opportunity for enabling the operator to determine without removing the plug from the cylinder whether the sparking terminals are properly functioning.

Having described the invention, what is claimed as new and useful is:

A spark plug comprising a shell, a nut engaging the shell, a core housed in the shell and nut, a gap chamber mounted upon the core, an electrode traversing the length of the core land having vone end disposed in said gap chamber, a terminal passing through the wall of the gap chamber andhaving an end located in the gap chamber and spaced from the terminal, the said nut having a gap chamber, a second terminal located in the last mentioned gap chamber and supported upon the core and 'spaced from the surface of the nut, an electrodey connected with the second mentioned terminal and passing through the core, both of said terminals having end portions .extending beyond the end of the core and spaced from each other, and a bridging electrode carried by the core and having an end portion disposed transversely of the ends of both of `the first mentioned electrodes and spaced therefrom.

In testimony whereof he aiixes his signature.4

LORENZO G. HOWARD. 

